Embodiments of the present invention relate generally to a display for measuring communication signal conditions and a signal analyzer, more specifically to a display for enabling one to easily measure power changes in time between a plurality of channels of multiplexed communication signals and a signal analyzer having such display.
Communication signals to be used in the W-CDMA type cellular phone system, or the like, are transmitted and received by multiplexing signals of a plurality of channels by a single carrier. A known signal analyzer for observing and measuring conditions of such communication signals is, for example, a wireless communication analyzer model WCA 200A commercially available from Tektronix, Inc. in the United States of America. This wireless communication analyzer comprises a spectrum analyzer based hardware in combination with a general purpose basic software operating system (OS) developed for personal computers and a plurality of application software that operate simultaneously in a plurality of windows. The installed application software allows the user to realize various functions that are suited for signal analysis of communication signals. FIG. 1 illustrates an exemplified graph that is available from a conventional signal analyzer using such application software. The upper half in FIG. 1 is a code domain power display, while the lower half is a codegram display.
A code domain display is disclosed in, for example, the specification of U.S. Pat. No. 6,219,340. Each bar in a code domain display represents an active channel and its width changes in response to the code layer on which the channel is located. For example, if the channel is on the code layer 2, eight (8) code channels are used. On the other hand, if the channel is on the code layer 3, sixteen (16) code channels are used. Accordingly, any channel on the code layer 3 is displayed with a double width of the channel on the code layer 2. The height of each bar represents power in dB.
A codegram display is disclosed in the specification of US patent publication no. 2004/0032897. The codegram display is considered to include all information of the code domain power display in addition to time changing information. The horizontal axis represents time. Similar to the code domain power display, each bar represents a channel and its width varies in response to the code layer on which the channel is located. Power is displayed in different colors.
Markers 6 and 8 are used respectively in the code domain power display and the codegram display for numerically displaying the corresponding channel name and power. Additionally, time information is also displayed in the codegram display. Such displays provide various information such as, for example, channels that are active, the code layer that an active channel is on, whether the channel is active, and the power level of the channel.
As apparent from the foregoing descriptions, the code domain power display and the codegram display are able to provide power level condition for each of a plurality of channels and how they change in time. Unfortunately, however, it was hard to understand the relationship between communication signals of a plurality of channels. Specifically, it was hard to recognize how each channel uses power with respect to the total power of the communication signal and how they change in time among a plurality of channels.